The treatment of waste, whether generated through municipal collection systems or through a broad range of industries, may be observed to vary from simple land-fill techniques to somewhat sophisticated chemical and biochemical conversion methods. With the latter methods, significant capital commitments generally are called for which require justification by virtue of environmental protection requirements and/or the generation of profitable by-products.
Controlled composting procedures are considered to offer significant promise for providing for an improved disposal of biodegradable industrial and municipal wastes while generating a somewhat valuable by-product. The preferred approach to treatment of wastes by biodegradation is one wherein composting is carried out in the thermophilic phase at temperatures of about 45.degree.-50.degree. C. At such temperatures, bacteria otherwise active in a mesophilic phase at lower temperatures are avoided and noxious odors are not present in the process.
To achieve thermophilic phase digestion, adequate aeration and agitation of the material is required. Generally, the approach to carrying out thermophilic digestion requiring the lowest capital investment is that of windrowing the waste material. With this approach, long rows of waste are developed which are laterally transferred and, consequently, aerated and agitated by a windrowing device. Thus, the waste material is progressively transferred from one row position to a next, for example, from right to left, across a treatment region over a period of time until a last row position is reached at which point the digestive process is completed and a valuable by-product is available for commercial sale. Such by-products find use, for example, as a surface treatment for strip mine soil reclamation or soil rejuvenation.
The type windrowing machine currently finding favor in the industry is one resembling a flight conveyor having a series of parallel, elongate paddles which are mutually interconnected by continuous chains and driven by a hydraulic motor. In operation, a rather large front end loader is utilized to suspend the conveyor at an angle both with respect to the ground and the axis of the windrow pile while moving forward at a relatively low speed, for instance 1 m.p.h., such that the lower disposed region or side of the conveyor confronts the row of material and, in effect, thrusts it into an adjacent row. Generally, these rows, which have a width of about 10-12 feet, will be transversely moved such that adjacent rows become spaced about 15 feet apart from center-to-center. The type of front end loader utilized for this procedure must be a dedicated one in view of the somewhat large and customized support arrangement for the conveyor. Typically, a 202 horsepower loader weighing about 26 tons is utilized. The dedication of the loader to the task of windrowing does not permit its additional convenient use as a loader per se in the treatment facility, a function which must be supplied by additional loading machinery and consequent added capital investment. Another difficulty ensues with the dedicated devices, inasmuch as at least two windrowing components, each with dedicated loader must be utilized. This requirement is occasioned, inasmuch as there inherently is a forward vector involved in the windrowing procedure such that the rows of material will tend to move forwardly as an entity. To counteract this movement, the windrowing devices must operate in a right and left reversal sense, one windrowing machine working from one end of the array of rows of waste material, while the other windrowing device operates in the opposite direction from the opposite side of the row array.